Vancomycin-Mediated Drug-Induced Immune Thrombocytopenia

Background: Except for the frequently occurring heparin-induced thrombocytopenia, drug- induced thrombocytopenias are a rare side effect of drug treatment. Since bleeding complications may be life- threatening, they require a fast and reliable diagnosis. A common problem, however, is to clearly identify the drug as the causative agent of the thrombocytopenic event. Case Report: The platelet count of a 72- year- old patient undergoing cardiac surgery and treated with vancomycin dropped to a nadir of 3,000/mul. Tests for the detection of drug- dependent antibodies using an indirect platelet immunofluorescence assay revealed vancomycin- dependent, platelet- reactive antibodies. Based on this case report, criteria and aspects of this drug- induced form of thrombocytopenia are discussed. Conclusions: In cases of drug- induced immune-mediated thrombocytopenia other than heparin-mediated, the detection of drug- dependent, platelet- directed antibodies should be accepted as a diagnostic criterion. Vancomycin- mediated immune thrombocytopenia may occur more frequently than suggested by the number of published cases.